Voice of the DBA

Author: way0utwest

  • Final Prep for SQL in the City

    I can’t believe this will be the fourth SQL in the City in London next week. It’s amazing to me that we’ve managed to build this great series of one day events that is so popular with SQL Server professionals.

    I’m heading back to London next week, a quick trip, but one I enjoy (once I’m there), as I get to see lots of old friends and meet new ones at the event. It’s always fun, and despite the long trip, it’s worth it.

    However I still have lots of prep. A few days off  this week to spend with my kids (I’ve been gone too much lately), so I’ll be pressed to finish my talks this week, and then have lots of rehearsals next week before I fly (and probably more while flying).

    If you’re in the UK and can get to London next Friday, we still have some space, and we’d love to talk to you about better database development, and administration, for your SQL Servers.

  • Document, then Install

    I saw someone post a note that they had installed a new SQL Server and wanted to document the install. Did anyone have a good script or process for doing this?

    I’ve done this myself, but lately it seems to be the wrong way of actually building systems. One of the things I have started to feel is important is that I should strive for consistency and known states for systems rather than works of art.  However if I’m installing systems and then documenting them, I think that I’m doing things backwards.

    There has been a trend towards declarative actions in technology, whereby we tell the system what we want and it configures itself to arrive in that state. An example of how some this can be done is with Puppet. This is a case of the administrator essentially documenting what they want to be done first, and then letting the system put itself in that state. It’s almost like programming the installation and configuration of software, but with tools to make the process much smoother.

    In this model, administrators don’t need to document the installs. They’ve already declared what needs to be done. If vendors change defaults in the future it doesn’t matter, as the installations will configure themselves to the same state, ignoring defaults and human expectations. This also results in much more consistently configured systems, something that’s critical for building a smooth software delivery pipeline.

    The closest thing I’ve seen to this for SQL Server is the Finebuild project that Ed Vassie set up. That’s much better than unattended installs and I’ve seen Finebuild demo’d, and it looks good. I need to set it up so that I can ensure that every instance I set up is in a known configuration. I can have multiple configurations ready, but I’d rather choose one of my choices and then let the system apply the settings than remember to click a particular check box or change some item manually. I’d also appreciate this for DR and auditing, with some list of settings for each instance or host.

    That just seems more like a 21st century way of working to me.

    Steve Jones

    The Voice of the DBA Podcast

    Listen to the MP3 Audio ( 2.6MB) podcast or subscribe to the feed at iTunes and LibSyn. 

  • Intermediate T-SQL: Window Functions

    This is the third hour of a three hour set of presentations on intermediate T-SQL techniques and features.

    This presentation covers the window functions that are available in SQL Server. Some of these functions were introduced in SQL Server 2005 and some in SQL Server 2015. We start with a brief introduction to what a window is, how a partition works, and then look at ordering and framing of rows. Then we cover the following in demonstrations:

    ROW_NUMBER()

    RANK(), DENSE_RANK(), and NTILE()

    The OVER clause and windowing in SQL Server 2012

    Using PARTITION BY and ORDER BY in the OVER clause

    Default framing with RANGE and how ROWS are different

    PERCENTILE() functions

    This covers a lot of information in an hour, but I try to use small data sets to explain what is happening with the window functions and how they can improve the performance, as well as simplify the code, for a number of common queries.

    Slides: TSQL_Windowing.pptx

    Code: TSQL_Windowing_code.zip

  • Intermediate T-SQL: PIVOT, UNPIVOT, and APPLY

    This is the second of a series of talks I put together on intermediate T-SQL topics that many database developers might not understand. In this talk, we cover the other join-type operators that exist in the FROM clause, outside of the INNER, OUTER, FULL, and CROSS join clauses. We break this hour into three main areas, covering:

    • PIVOT and crosstabs
    • UNPIVOT
    • APPLY

    Most of the time is spent on the APPLY operator, which is arguably the most useful of the three. I show how APPLY is like an inner or outer join, and also how it can be used to improve performance of a scalar function, how it can be used to run some queries that are difficult with INNER JOINs, and how we can use this to easily find query plans and code in performance tuning.

    The PIVOT operator is compared to a crosstab, which is similar. We see how to write a query using either method. We also show the UNPIVOT operator.

    Slides: TSQL_IntermediateQueries.pptx

    Code: TSQLPIVOT_Unpivot_Apply.zip